Warning: MAJOR SPOILERS for Avengers: Endgame ahead!
Since 2008’s Iron Man, Robert Downey Jr. has been on a journey with Tony Stark, and in that time the Marvel Cinematic Universe has grown in stature and scope around him. While that growth will continue, it would appear it will now be without Robert Downey Jr. because in Avengers: Endgame, Tony Stark sacrificed himself by using the Infinity Stones to defeat Thanos.
It was a heroic and poetic end for the character, closing out the Infinity Saga and these first 11 years of the MCU by circling around back to its beginning. But how did Robert Downey Jr. feel about it? While speaking about how the film's actors responded to their character’s fates, co-director Anthony Russo addressed just that. He said:
A lot of the actors are not opinionated about what we do. They like the fact that we are sort of in control of these stories and we are driving where they should go and we have a vision for where they should go and they trust in that. I think Downey may have had mixed emotions about thinking about [where Tony Stark ends up in Endgame], but I think at the end of the day, he totally accepted it.
By the sound of it, Robert Downey Jr. wasn’t completely gung-ho about what happens to Tony Stark in Avengers: Endgame. Unlike some of the other actors in the cast who had a more laissez faire attitude towards where their characters went, happy to let the writers and filmmakers decide, it sounds Robert Downey Jr. had his own opinions. Which, if we're being honest, totally fits for the guy who plays Tony Stark.
The Russo Brothers pitched Robert Downey Jr. Tony Stark’s arc in the film to make sure that he was comfortable with it. Although he ultimately accepted it and was cool with what happened, based on what Anthony Russo told THR, the actor had some mixed feelings about where Tony Stark ends up in the film.
It will be interesting to hear from Robert Downey Jr. himself about what he thought of Tony Stark’s fate in Avengers: Endgame and why he felt however he did, but mixed emotions are certainly understandable. The actor has spent over a decade with this character, so he likely had a great deal of investment in Tony Stark and his own ideas about what would happen to him and how his story should end.
This is purely conjecture, but maybe Robert Downey Jr. liked that Tony Stark got a poetic and heroic end, but had hoped that he wouldn’t die at all. So he may have accepted and appreciated the ending on a story level, but still wished that this character that he played for so long and was paid so handsomely for could have survived. Maybe he preferred a purely happy ending where Tony and Pepper lived happily ever after and he got to watch Morgan grow up.
The fact that Robert Downey Jr. had mixed emotions about the end of Tony Stark’s arc reminds me a bit of Mark Hamill’s feelings about Luke Skywalker in Star Wars: The Last Jedi. While that was a case of Mark Hamill being somewhat vocal in his disagreement with his character’s choices in the film, it was also an instance of an actor who genuinely cared about his character and had opinions and ideas about the way his story should go.